Connections between reservoir cells and numerical aquifer cells, or
between numerical aquifer cells when multiple such cells define a
single numerical aquifer, should always be treated as NNCs for
output purposes and end up in the (NNC1,NNC2,TRANNNC) output arrays.
To this end, make a special purpose predicate to identify numerical
aquifer connections when forming the output NNC and transmissibility
arrays and act accordingly in member functions 'computeTrans_()' and
'exportNncStructure_()'.
While here, also pick up the NNC transmissibility value from
'globalTrans()' since multiplier operations like MULTREGT might have
affected the explicit values entered in the NNC, EDITNNC, and
EDITNNCR keywords. This is in preparation of properly incorporating
such multipliers in follow-up work. Finally, fix a subtle problem
caused by using 'std::abs()' to check for non-zero connections.
When accounting for explicit NNCs, it might happen that the final
transmissibility would become negative with a sufficiently large
absolute value that 'abs(t) > threshold' would be true. This would
result in outputting a negative transmissibility value to the NNC
arrays which would confuse result processors.
